Transmission Control Protocol (TCP) is used to facilitate communication between applications of a transmitting network device and a receiving network device using the Internet Protocol (IP). In particular, when a transmitting network device transmits data across a network (e.g., the Internet), application layer software on the transmitting network device issues a request using the TCP layer. The TCP layer handles routing and SEND/ACK details to ensure delivery of the data to the receiving network device.
Network congestion, traffic load balancing, or unpredictable network behavior can cause data packets to be lost, duplicated, or delivered out of order between transmitting and receiving network devices. The TCP layer detects these problems, requests retransmission of lost packets, rearranges out-of-order packets, and/or minimizes network congestion to mitigate anomalous activity. Once the receiving network device has reassembled data packets sent from the transmitting network device, it passes the data packets to the application running on the receiving network device.
When data packets are transmitted between transmitting and receiving network devices, rate or traffic shaping is used by a rate shaper of the transmitting network device to control the rate of flow at which data is transmitted. Typically, the receiving network device continually informs the transmitting network device as to how much data it can receive. When a buffer of the receiving network device fills with data, a subsequent acknowledgment sent to the transmitting network device includes a notification to suspend or stop sending data until the receiving network device is able to process the previously received data packets.
Network performance is generally maintained by using Quality of Service (QoS) functionality performed by the rate shaper, including as a QoS queue. Typically, a transmitting network device packetizes data in accordance with the TCP and sends the data packets to the QoS queue associated with a receiving network device (also referred to as a subscriber). The QoS queue stores the packetized packets and buffers them before transmitting them to control the traffic flow based on predetermined handling parameters. However, this process generally requires performing an enqueue and a dequeue of every packet, which can introduce significant overhead to the process. Additionally, QoS queues, as well as associated token buckets and timers, are not efficiently scalable, and therefore require significant resources to manage a large number of subscribers, which is undesirable.